Hydrocarbons 2 Question 7
7. The trans-alkenes are formed by the reduction of alkynes with
(2018 Main)
(a) $\mathrm{H}{2}-\mathrm{Pd} / \mathrm{C}, \mathrm{BaSO}{4}$
(b) $\mathrm{NaBH}_{4}$
(c) $\mathrm{Na} /$ liq. $\mathrm{NH}_{3}$
(d) $\mathrm{Sn}-\mathrm{HCl}$
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Answer:
Correct Answer: 7. (d)
Solution:
- Sodium metal in liquid ammonia reduces alkynes with anti stereochemistry to give trans alkenes. The reduction is selectively anti since the vinyl radical formed during reduction is more stable in trans configuration.
Mechanism
